Katha Upanishad Verse 2.3.13

The seeker should first understand that the Atman exists and then realize Its essential nature as It truly is. To the seeker who starts with the firm conviction of Its existence, the Atman’s real, essential nature eventually reveals itself.

Sanskrit Verse

अस्तीत्येवोपलब्धव्यस्तत्त्वभावेन चोभयोः ।
अस्तीत्येवोपलब्धस्य तत्त्वभावः प्रसीदति ॥ १३ ॥

Transliteration

astītyevopalabdhavyastattvabhāvena cobhayoḥ |
astītyevopalabdhasya tattvabhāvaḥ prasīdati || 13 ||

Translation

He should be known to exist and also as he really is. Of these two, to him who knows him to exist, his real nature becomes revealed.